GP
lenses may not be the hot topic in contact lenses at the moment, but they do garner
between 10 and 13% of the U.S. contact lens market. And GP patients are seven times
as likely to return to your office for follow-up. New GP lens designs offer more
options for mature presbyopes, pellucid marginal degeneration, keratoconus, irregular
astigmatism, corneal reshaping and more.

Here we'll explain the benefits of the latest FDA-approved
designs. Manufacturers also offer new fitting guides and diagnostic fitting sets
to address previous visual, ocular health and comfort problems. Some improvements
include the ability to successfully fit presbyopes who require higher adds and work
with corneal irregularities

While GPs must compete with soft lens options for many conditions,
presbyopia is one area that still holds the potential for GP market growth. "This
is the largest segment of the population," says Mike Johnson, director of consultation
at Art Optical. "It's the last frontier for GPs." Multifocal GP sales saw a 20%
increase last year. Lee Dickerson, president of ABBA Optical and immediate past
president of the Contact Lens Manufacturers Association (CLMA), believes this is
due in part to the development of new lens designs. "Many practitioners are now
leaning away from prescribing monovision now that we have developed good multifocal
and bifocal lenses," he says.

New designs offer mature presbyopes more add power, without sacrificing
comfort. Many of today's multifocal lenses have large distance and intermediate
zone diameters to provide sufficient movement.

Some multifocals add more power to the front surface. This allows
you to adjust a presbyope's prescription without the need to switch to another lens.
"Because presbyopia progresses with time, it often means a change in asphericity
to accommodate more add, but this ultimately changes the fit of the lens. By compensating
on the front surface, we avoid that problem," explains Jean Blanchard, president
of Blanchard Contact Lens.

However, "There is no single lens that will take care of all presbyopic
patients," says Mr. Dickerson. That's why there are many lens options for you to
choose from for this group.

Irregular corneas

Keratoconic corneas are among the most difficult to fit. "These
patients present a unique fitting situation because no two cones are alike," says
Mr. Dickerson. But dissemination of topography has increased the chances of a successful
keratoconus fit. "More and more cones are detected early with increased use of topography,"
says Mr. Blanchard. And early fitting is key. "If a cone patient is fit with-in
the early stage with a keratoconic-specific design, the risk of abrasion or progression
is greatly reduced, by optimizing lens position, tear exchange, comfort and long-term
corneal health."

In many cases, you can send a patient's topography directly to
the lab that will base the lens design on the patient's data. "Any time we can get
topography for a keratoconus patient, it makes it easier," says Mr. Johnson.

The high-minus lenses these patients generally require create
additional spherical aberration. However, lenses that modify the curve and incorporate
asphericity on to the back surface of the lens can "counteract the natural spherical
aberration in high-minus lenses," says Mr. Blanchard. To address the appearance
of halos, some new lenses feature a larger optical zone.

Some keratoconus lens designs allow you to make peripheral changes
in different quadrants of the lens without changing the base curve, diameter or
optic zone. Jan Svochak, vice president of Tru Form Optics, says, "More symmetrical
pooling around the outside of the lens maintains a light touch on the tip of the
cone." Other lenses incorporate additional curves into the lens to match the keratoconus
mid-peripheral slope.

Another option for tough-to-fit presbyopes is scleral or semi-scleral
lenses. "For patients who have undergone penetrating keratoplasty, or those with
other highly-irregular corneas, a scleral or semi-scleral lens that fits out past
the limbal margin can provide a smooth wavefront, but also doesn't depend on the
cornea for centration," says Mr. Dickerson. "Plus since it's so large, it's generally
very comfortable with a well-fitting lens."

Ortho-K

The lens on the top was treated with a plasma
coat, the one on the bottom was not.

Orthokeratology (Ortho-K), also known as corneal reshaping or
corneal refractive therapy (CRT), is another area where GP lenses have an advantage.
"We feel this is a great opportunity for the marketplace because it's strictly done
with GP lenses," says Mr. Blanchard. But this modality hasn't met expectations.
"We hoped ortho-k would spark a bigger interest and practitioners would jump on
the band wagon, but that just hasn't happened," says Mr. Johnson. But the lag time
may be related to the training requirements and patient selection guidelines.

Dan
Bell, president of Corneal Design and of the CLMA, suggests consulting the organization
for help. "Optometric practitioners benefit from our many decades experienced contact
lens technician consultants," he says.

Dispensing aids

GP labs have also introduced new tools to help you work with the
latest designs and find the best fit for your patients. ABBA Optical's multiple
visual performance (MVP) dispensing system allows practitioners to dispense custom
multifocal lenses immediately. This allows you to offer patients a free in-office
trial of a GP lens with out the inconvenience of follow-up visits or additional
fees. Base your initial lens selection on the flattest K and spherical refractive
error. Power refinement is similar to soft multifocals. ABBA will also provide customized
patient brochures free of charge to those who own the system.

Art
Optical's Art Keratoconic System (AKS) loaner cone series is intended to help you
control the lens' optical diameter according to the base curve relationship. Two
sets are available: base curves for the standard set range from 6mm to 7.2mm in
0.10mm steps; the extended set ranges from 5mm to 6.2mm. All lenses have a diameter
of 8.5mm, while the optical zone diameter reduces as the base curve steepens. By
controlling the optical zone to relatively match the base curve, you can avoid seal
off or 360Þ bearing. The powers in the loaner set are also controlled to increase
in minus power as the base curve steepens.

Lens treatments

The latest advancement in GP coatings is the plasma coat. Paragon
Vision Sciences' Aqua Comfort cold gas plasma coating treatment provides improved
wettability. ABBA Optical utilizes the process under the name Hydrolize and Bausch
& Lomb is awaiting approval on a similar treatment. "The plasma process that
is applied to the surface of many GP lenses today so dramatically increases the
initial comfort that it will increase the GP market share," says Mr. Dickerson.
"GP lenses can create wettability and deposit issues," says Mr. Johnson. A study
conducted by Paragon shows the treatment enhances patient comfort for: dry eyes,
oily or filmy contact lenses, and high-Dk lenses that are less wettable. Because
plasma treatment makes GPs more comfortable, it may also reduce new wearer adaptation
time.

What the future holds

Labs continue to make improvements on lens designs and treatments.
But some believe it's time for a shake-up in the GP market. "To take specialty lenses
to the next level, we will need something revolutionary in terms of material itself,"
says Mr. Blanchard. "There is a limit to what we can produce design-wise." Until
a new GP material is introduced, however, labs will continue to work on current
designs and materials to provide your GP patients better options and keep them coming
back to your office.

For more information or assistance with GP lenses, contact the
CLMA at www.clma.net, and/or the GP Lens Institute (GPLI) at
www.gpli.info.

Dr.
Anan Kogan has worn GP lenses
since 1980 and published over 125 contact lens articles. She also served as public
relations director for Northern Virginia Optometric Society and for Dade County
Optometric Association, Florida. Her practice focused on designing and consulting
with CLMA labs, with a specialty in orthokeratology.